Article packaging machines are commonly used to package articles such as soft drinks and beer into cartons for storage and display. An example of such a packaging machine is shown in U.S. patent application Ser. No. 08/118,111. In general, most article packaging machines include a conveyor for moving cartons along a path in spaced sequential relationship. As the cartons are conveyed along the path, adjacent sections of the machine function to insert articles such as beverage cans into the cartons whereupon the cartons are progressively sealed and moved out of the machine for collection and transport.
Most carton conveyors in packaging machines include a conveyor bed having spaced arrays of upstanding lugs that function to space the cartons on the conveyor bed and push them along the path in their spaced sequential relationship for packaging. In some packaging machines, such as that disclosed in the referenced patent application, the spacing between the conveyor lugs is variable to accommodate cartons of different widths. For example, in beverage container packaging machines, cartons are commonly either 51/4 inches wide or 111/4 inches wide depending upon the number of articles packaged in the carton. Thus, conveyor lugs on these machines generally are adjustable to provide either 6 inch or 12 inch spacing between lugs to accommodate cartons of either width.
A common problem with article packaging machines, and with beverage container packaging machines in particular, is that the top portions of empty open cartons being conveyed along the path tend to drag or lag behind the bottom portions that are held in place and pushed by the conveyor lugs. This causes the cartons to become deformed as they move along the path. As a result, articles cannot be inserted easily into the cartons and, in fact, can impact the skewed cartons causing a machine jamb. To address this problem, many packaging machines employ an overhead pusher lug assembly to support and brace the top portions of cartons as they move along the path. While such overhead pusher lug assemblies vary in detailed operation, in general they comprise an endless flexible conveyor such as a chain having a lower flight that is positioned above the tops of the cartons and moves along in synchronization therewith. An array of downwardly projecting lugs are fixed to the chain and extend into the spaces between cartons to engage and support the top portions of cartons as they move along the path. As a result, the cartons are maintained in their square undeformed orientations for easy insertion of articles.
In the past, overhead pusher lug assemblies have exhibited numerous problems and shortcomings. For example, it is desirable that the lugs of the assembly extend as far as possible into the space between the cartons to provide maximum area of engagement for supporting the cartons. Unfortunately, the length of the lugs is naturally limited by the close spacing of the cartons on the conveyor. For example, as each lug moves around its drive sprocket at the upstream end of the carton conveyor and onto the lower flight of its conveyor, it also moves into the position between two adjacent cartons. If the lug is too long or if the carton spacing is a bit less than expected, the lug will impact the top corner of the trailing carton as it rounds the sprocket thereby deforming the carton. As a result, the entire packaging machine must be shut down and the deformed carton replaced before the packaging operation can be resumed.
Another problem with prior art overhead pusher lug mechanisms is that they have not been easily adaptable to cartons of different widths. Usually, when setting up the machine for a different width carton, lugs on the overhead pusher lug assembly have to be manually removed and refixed to their conveyor chain at the desired spaced intervals. Obviously, such a procedure is time consuming and requires the knowledge and resources of valuable trained personnel. Such manual adjustment of the overhead pusher lug spacing is particularly troublesome on modern beverage packaging machines where the lugs on the carton conveyor itself typically are easily and quickly adjustable.
Accordingly, there exists a continuing and heretofore unaddressed need for an efficient effective overhead pusher lug assembly for packaging machines wherein the size of the individual lugs is not unreasonably limited by the danger of the lugs impacting and deforming cartons as they move around their sprockets and between the cartons on the carton conveyor. A further need exists for an overhead pusher lug assembly that is quickly and easily adjustable to accommodate cartons of different widths on the carton conveyor. It is to the provision of such an overhead pusher lug assembly that the present invention is primarily directed.